Question

Carbon and hydrogen are detected by heating the organic compound with _______.

• A. Magnesium oxide
• B. Cupric oxide
• C. Zinc oxide
• D. Sulphur dioxide

Answer 1

The correct option is B Cupric oxide

The detection of various elements present in an organic compound is called qualitative analysis. Carbon and hydrogen are present in almost all the organic compounds. Carbon and hydrogen are detected by heating the organic compound with cupric oxide $\left(CuO\right)$ strongly, where carbon is oxidized to carbon dioxide and hydrogen to water. Carbon dioxide is tested by lime water test, whereas water is tested by anhydrous copper sulphate test.
Detection of C:
$C+2CuO\stackrel{\Delta }{\to }CO2+2Cu$
$C{O}_2+2Ca(OH{)}_2\stackrel{\Delta }{\to }CaC{O}_3+H_{2}O$

Detection of H:
$2H+CuO\stackrel{\Delta }{\to }{H}_{2}O+Cu$
$CuS{O}_4+5H_{2}O\stackrel{\Delta }{\to }CuSO4.5H_{2}O$